The present invention relates generally to an electrical gas-blast circuit breaker having several spaces which are filled with a quenching gas.
From the introduction to the description of German Auslegeschrift No. 1,102,858, it is known to subdivide electrical circuit breakers, which are filled with a gaseous quenching agent, into individual spaces. In this way, the quenching agent of each individual space may be maintained under a different pressure. In such an arrangement, the individual spaces can be connected to one another only via valves. Because of the different pressures prevailing in each of the individual spaces, a flow of the quenching agent, which is intended to quench the arc when breaking the circuit, is produced by opening the valves. Accordingly, the valves are open only upon switching of the circuit breaker.
Furthermore, in German Offenlegungsschrift No. 1,102,858, an electrical circuit breaker is described which is filled with a gaseous quenching agent. The agent may be sulphur hexafluoride and/or selenium hexafluoride with the circuit breaker sub-divided into several closed spaces (e.g. break chamber, actuating head and support insulator). The several closed spaces are connected to one another only by way of valves which close at a predetermined pressure difference between two spaces of the circuit breaker. During normal operation, all of the components of the circuit breaker or all of the spaces are accordingly connected to one another so that the quenching agent can circulate unhindered between the spaces. Furthermore, all of the gas contained in the circuit breaker is thus available for quenching the arc.
In the last-mentioned circuit breaker, the valves are accordingly constructed in such a way that the valves close immediately in the event of a predetermined pressure difference between two spaces. In this way, in the event that one part of the housing of the circuit breaker is leaking, the gas can only flow out of that part of the circuit breaker which is immediately affected.
In the known circuit breakers described above, the valves thus are arranged, when opened, to reduce an existing pressure difference of the quenching agent by way of a flow of quenching agent between the spaces filled with quenching gas or, if a pressure difference of the quenching agent arises between the spaces as a result of closing the valves, of preventing the generation of a flow of quenching agent by mutually isolating the spaces. In this way, it is completely impossible in view of the known prior art to achieve the objects of the present invention, using circuit breakers of the known type.
Accordingly, it is a principal object of the present invention to produce electrical gas-blast circuit breakers at a place of manufacture in various components so that one need only assemble the components together as transportation units in a very simple manner at the place of ultimate assembly. Such assembly may occur even under climatically unfavorable conditions. If necessary, only the pressure of the quenching gas in circuit breakers assembled according to the present invention needs to be varied in accordance with the operating conditions.
One of the advantages achieved by the present invention is that the circuit breaker can be manufactured in the form of a plurality of switch assemblies. The assemblies are filled with quenching gas at the place of production and are absolutely free from moisture and dust and are largely unaffected by the particular climatic conditions.
The quenching chambers together with the deflection chamber, that is to say the entire two-component circuit breaker unit, and the earth insulation or the insulator are at the same time constructed as automatically gas-tight transportable units in such a way that, upon assembly of the transportable units filled with quenching gas (or of the switch assemblies), the gas spaces of the unit are automatically connected in an advantageous manner to give a single gas space. Upon dismantling of the switch, the units can be taken apart again into switch assemblies which automatically become gas-tight.
Evacuation of circuit breakers mounted in the switching unit is thus unnecessary since the particular switch assemblies, and at the same time the transportable units, can be forwarded, already filled with the working gas from the place of production to the place of destination.
Furthermore, another advantage results since the circuit breaker can be assembled largely independently of the weather. Since it is no longer necessary to open the switch assemblies and the components (which merely have to be connected directly to one another), the assemblies can easily be kept free from moisture and dust. Accordingly, a great shortened assembly time results from the simplified assembly.
The present invention also results in considerable advantages with respect to maintenance of the circuit breaker and the replacement of components of the circuit breaker.
It was hitherto necessary to dismantle the circuit breakers and (in the event of the customarily relatively large constructional unit), to take the units, sub-divided into components, into a maintenance shed. As a result, the interior of the circuit breaker was already exposed, at least for the duration of transportation to the maintenance shed, to the ambient moist or dust-enriched atmosphere. Such an exposure had to be avoided under all circumstances, in particular in the case of SF.sub.6 circuit breakers, because of the primary and secondary decomposition products and because of the subsequent reaction products of H.sub.2 F.sub.2.
According to the present invention, the avoidance of exposure now becomes possible without difficulty in an advantageous manner since even large circuit breakers can be dismantled into the various switch assemblies. These gas-tight transportable units can then be transported into the maintenance shed without being adversely affected by the atmosphere.
Opening of a particular switch assembly, which may sometimes be necessary, can accordingly take place in the maintenance shed (which is under climatically controlled dust-free conditions). The cleaning of the interior of the assembly can therefore be carried out without the pressure of time, such as occurs in the case of circuit breakers which have to be opened outdoors, since an adverse influence of moisture on the interior of the circuit breaker cannot arise in the dry atmosphere of the maintenance shed.
A further advantage according to the present invention is that the successive cleaning of the circuit breaker in switch assemblies can be carried out by fewer people than is presently possible with circuit breakers that are opened outdoors.
Moreover, replacement in situ of quenching chambers or two-component circuit breaker units, which are correspondingly constructed according to the present invention to be automatically gas-tight, is possible in a very simple manner. It is not necessary, therefore, that the pole be evacuated and cleaned in a costly manner at the building site or in the switching unit.
It is particularly advantageous to construct the circuit breaker in order to achieve in a simple manner, in the case of circuit breaker components which can move relative to one another, a gas-tight closure in the region of the edge zone of the assemblies. Such a gas-tight closure is desirable at least in the transportation arrangement of the assembly by stationary gas-tight devices or seals.
A further advantage of the present invention includes the use of devices which can be switched over from a gas-tight to a gas-permeable condition and vice versa and which are located in fixed circuit breaker components in the region of the edge zone of the assemblies. In this way, a connection of the spaces, filled with quenching gas, of these assemblies is achieved automatically upon assembly of the switch assemblies, and a gas-tight closure is effected automatically in the region of the edge zones of the assemblies and ensured by the same devices and in an equally simple manner solely by taking the circuit breaker apart into its abovementioned switch assemblies.
According to a preferred embodiment of the present invention, the circuit breaker is constructed so that the switch assemblies, in combination with transportation covers, can both be transported and also be stored in a gas-tight condition for a prolonged period. Such an arrangement leads to the further advantage that the components of the circuit breaker, present in the switch assemblies, are fixed in the transportation position by the transportation covers.
It is also advantageous to construct the circuit breaker in order to connect the spaces within the switch assemblies and the associated transportation covers to one another in a simple manner and to enable the switch assemblies to be evacuated and pre-filled with quenching gas in a very simple manner via gas passage orifices in the transportation cover or in an insulator flange.